NEW DELHI: The Supreme Court today wondered why Arvind Kejriwal-led government's much hyped Odd-Even scheme has not been able to reduce pollution level and steps taken to achieve ambient air quality standards seemed not to be working.

"Why no difference is made out in pollution level in Delhi, even after steps have been taken like odd-even scheme, diversion of trucks from the national capital. What are the solutions," a bench headed by Chief Justice T S Thakur asked while hearing a PIL filed in 1985 to check pollution levels.

The bench also comprising Justices A K Sikri and R Banumathi, which gave a special hearing on Saturday, said that earlier, the trucks used to ply through the centre of the national capital but now they have been diverted but still no difference seems to have been made in improving the ambient air quality.

Senior advocate Abhishek Manu Singhvi appearing for the automobile manufacturers said that there are several other factors which contribute to pollution which include road dust which is 38 per cent and industries which contribute 11 per cent.

"Unless we look and address the issue of real pollutant, nothing will seem to improve," Singhvi said without commenting on the Odd-Even scheme whose second phase will end today.

Singhvi further said, "to say diesel cars cause more pollution and therefore we should ban them will solve no problem."

The second phase of Odd-Even scheme started on April 15 under which vehicles with odd or even registration numbers ply on alternate days ended today. The first phase of Odd-Even scheme was first launched on January 1 to January 15.

Chief Justice of India T S Thakur, earlier in December, had virtually endorsed the Delhi government's decision to allow plying of private vehicles bearing odd and even registration numbers on alternate days to lower pollution levels, saying it can be followed "if it helps in reducing" the problem.

He had said that he was not averse to pooling vehicle with brother judges.